The overall objective of the proposed research is to generate a profile of the behavioral pharmacology of PCP in comparison to four other abused drugs with complex operant tasks involving learning and memory. The technique of repeated acquisition will be used to study drug effects on learning (with and without added stimuli) in primates under five different baseline conditions. Multiple schedules will be used in order to make a direct comparison of drug effects on learning and performance. Matching-to-sample procedures will also be employed to evaluate drug effects on shortterm memory. The major research effort will concentrate on the following experiments with primates. Acute dose-effect data will be obtained for PCP and for pentobarbital, d-amphetamine, MDA and ketamine. The behavioral effects of chronic PCP administration and the extent of cross-tolerance to the other drugs will also be determined. The proposed research will also focus on interactions between PCP and pentobarbital and between PCP and haloperidol. Additionally, pigeons will be used to determine whether the effects of PCP on repeated acquisition can be modified by manipulating the schedule of reinforcement.